Circuit interrupter



Dec. 28, 1943. J. K. HODNETTE 2,337,320

CIRCUIT INTERRUPTER Filed Oct. 50, 1941 6 Shets-Sheet 2 F493 V P Fig. 4.

1. 6 4% Johnjfi'Hod/zeffe novel circuit breaker operating mechanis shall be effective to lock the breaker conta Patented Dec. 28, 1943 accuses ziuazo? PAT NT OFFICE I cracurr m'rnaaurrnn John K. Hodnette, Sharon, Pa, assignor to West inghouse lectric &

Manufacturing Company,

East Pitts urgh, Pa, a corporation of hennsyl Vania Application Gctober 3%,1941; Serial-No. ll'ldlfib This invention relates to electric circuit interrupters generally, and more specifically to circuit breakers especially of the automatic reclosing type. l

At the present time. it is common practice to protect individual distribution transformers and branch feeder circuits with a fuse having a metallic link which melts on overcurrents to interrupt the circuit. Most fuses'are open to the atmosphere and consequently may give iaulty-operation due to oxidation and deterioration of the link. The life of a fuse is limited to a iew operations, and after blowing the fusible link must be manually replaced to restore service-on the circuit protected. To overcome the last of these disadvantages, so-c'alled repeating fuses have recently been used. Thesecomprise a plurality of fuses with one normally in the circuit, and with automatic means for connecting another in the circuit when said one fuse blows. Although this type of fuse structure provides for better continuity of service, blown fuses must still be manually replaced, and they are also subject to the other disadvantages oi iuses set forth above. To overcome the above-mentioned disadvantages of fuses, it has been. proposed to provide an automatic reclosing oil circuit breaker as a protective device to replace fuse structures. Such circuit breakers mustbe made small in size so as to be suitable for pole mounting, they should be completely self-contained, and should oper- I ate to lock the breaker contacts open after a predetermined number of reclosures, and reset to their original position following any number of reclosures less than said predetermined number. Thus far, the art has failed to develop a fullysatisfactory circuit breaker of this type which satisfies all of the foregoing requirements rela tive to size'and operating characteristics.

Accordingly, one object oi this invention is to provide anovel. small automatic reclosing circuit breaker o! the type described.

Another object of this invention is to provide cts in open circuit position only in response to a predetermined number of closely successive circuit interrupting operations. a

Another object of this invention'is to provide is to provide m which in a circuit breaker of the type described, novel means :Eor mechanically separating the breaker contacts at least enough to draw an arc in response to predetermined circuit conditions.

Another object of this invention is to provide a circuit breaker of the type described with electrore'sponsive means for both opening and clos- 'ingthe breaker contacts.

Still another object of this invention is to profluid pressure generated by the arc to fully separate the breaker contacts, additional means responsive to persistent small current arcs for positively separating the breaker contacts.

These and other objects of this inventionwill become more apparent upon consideration of the following detailed description of preferred embodiments thereof taken in connection with ,the attached drawingain which:

Figure 1 is a longitudinal cross-section view of a circuit breaker constructed in accordance with one embodiment of the invention;

Fig. 2 is a central longitudinal cross-sectional view similar to Fig. l, but taken at right angles to the section of Fig. 1; V

Fig. 3 is an enlarged view oi the operating mechanism shown in Fig. i;

Fig. 4 is an enlargedview of the operating mechanism as shown in Fig. 2 of the drawings; 301 Fig. 5 is a-view similar to Fig. 3, but showing the parts in a position wherein the circuit break-, er contacts are open corresponding to an initial circuit interrupting operation;

Fig.1} is a view similar to Fig. 5, but

shows the parts in a position wherein the circuit breaker contacts are locked open; I

Fig. 7 is a longitudinal cross-sectional view of a circuit breaker illustrating another embodiment of the invention;

Fig. 8 is a partiallongitudinal cross-sectional view illustrating a modified form of contact operating mechanism;

Fig. 9 is a. view similar. to Fig. 8, but showing a still further modified form' of contact operat- 5 ing mechanism; y

Fig. 10 is a longitudinal cross-sectional View of another modified form of circuit breakerper Fi 11 isan elevational view partially in section of a still further modified form of circuit breaker operating mechanism; and

Fig; 12. isa partial longitudinal crosssectional view of still another modified form of circuit breaker constructed in accordance with. this 111: v ntion.

vide in a circuit breaker ,of the type utilizing In the drawings there is illustrated reclosing circuit breaker construction wherein the contacts are first initially opened by mechanical means controlled by a current-responsive element, together with means for biasing the contacts closed following a circuit interrupting D- eration. There is also provided means responsive to a predetermined number of successiv interrupting operations to lock the breaker contacts open, and in the event of the occurrence of successive interrupting operations less than said predetermined number, the lookout means is adapted to be reset so that the apparatus will be in condition to lock the contacts open in the event of the occurrence of said predetermined number of interrupting operations in th future. The breaker illustrated in the drawings also is especially constructed so that pressures developed by the are formed when the contacts are initially separated aid to obtain further separation of the contacts irrespective of the current value of the arc.

Referring to the drawings, there is shown in Figs. 1 to 6 a circuit breaker which may be 'enclosed in an insulating casing 2 which may be of any desired insulating material, preferably porcelain oiythe like, and which has an open top and closed bottom, as viewed in Figs. 1 and 2.

The closed bottom of casing 2 is provided with' a substantially central aperture 4 for the reception of a terminal bolt 6 having an enlarged head 8 adapted to be positioned interiorly of casing 2, with packing material l0 interposed between the head of the bolt and casing wall to seal opening 4. Contact bolt 6 is secured in position by a nut i2, with a Washer l3 interposed between the nut and casing 2, and a second nut l6 may be provided on bolt 6 for securing a conductor l4 thereto.

Casing 2 is preferably provided intermediate its ends with a smooth outer peripheral surface l8 for reception of a clamping strip or other se-- curing means for supporting the interrupter on a cross-arm or other support. The upper end of casing 2 is provided with a supporting channel member secured to the casing, for example, as by molten material poured in between the channel and casing and forming locking projections between integral rib 22 on the outer surface of the casing. The support 20 is for the purpose of securing a casing cover in operative position with respect to the casing.

A cover assembly 26 is shown as mounted over the open top of the casing and includes a generally tubular casting 28 having a peripheral flange 30 adapted to be seated on the open end of the casing, and be secured to support 20 in any desired manner 'not shown The particular insulating casing described above, together with the bottom contact assembly therefor, and support 20 for a casing cover are substantially like those disclosed and claimed in the copending applications of J. M. Wallace, Serial No. 345,051, filed Jul 12. 1940, and H. L. Rawlins, et 211., Serial No. 346,300, filed July 19, 1940, now Patent. No. 2,318,431 granted Ma 1943, both assigned to the same assiguee as this invention. Accordingly, for a inormcomplcte description of this structure. reference is hereby madr to the above-identified copcnding applications.

The circuit breaker operating mechanism is supported from cover assembly 26 by an insulating supporting plate 32. which may be of any desired insulating material, such as fibre or the like, and secured to cover casting 28, ior example, as by bolts 34. A supporting column 36 for the interrupter chamber 42 and operating mechanism is preferably secured to the lower end of insulating supporting plate 32, for example, as by bolts 36, and the lower end of the supporting column is preferably fixed to, or may b integral with, a top cap 40 of the interrupter unit 42. The interrupter unit includes an insulating tube 44 which also may be made of any, desired insulating material, preferably fibre or th like, and this tube is threaded at each end thereof for securement to top cap 40 and lower end cap 46. It will be noted that lower end cap 46 has a reduced outer end portion forming a shoulder 48 on which one end of a coil compression spring 56 is adapted to be seated, with the other end thereof bearing against the head 6 of contact bolt 6 to insure good electrical contact under Dressure between end cap 46 and bolt 6. Coil spring 56 may be of any desired resilient conducting material, such, for example, as a copper alloy. Lower end cap 46 is provided with a threaded aperture substantially centrally thereof for receiving a renewable contact 52 adapted to be engaged by the lower end of a movable contact rod 54, slidably mounted through a substantially central aperture in upper end cap 40.

The are chamber 42 is preferably subdivided into a plurality of compartments and, as shown, this is accomplished by providing a plurality of disk-like partitions 56 and 58 in insulating tube 44, and a lower partition 66 which forms a relatively small compartment within which contact rod 54 engages renewable contact 52. Partition 60 preferably has the lower surface thereof inclined, as shown at'62, to form the aforesaid relatively small compartment together with end cap 46. The partitions 56, 58 and 60 are maintained in spaced relation within insulating tube 54 by spacer rings 59 and 6t, also preferably of insulating material like partitions 56, 56 and 66.

In the operation of the arc chamber thus far described, it will be apparent that when contact rod 54 is moved away from renewable contact 52 and an arc is struck therebetween, and assumingthe arc chamber to be filled with an arc extinguishing fluid, such as oil, it will be obvious that the action of the are on the oil will cause decomposition thereof and create a fluid pressure first within the relatively small chamber between partition 60 and end cap 46. If the arc current is high, this pressure will act on contact rod 54 in a piston-like manner to cause further movement thereof away from renewable contact 52 and draw out the are successively through the compartments of the arc chamber defined by end cap 46 and partitions 60, 58 and 56, Such large current arcs, therefore, will be exposed successively to an increasingly large arc chamber space, besides being subjected to relatively fresh reservoirs of arc extinguishing fluid maintained in the several compartments. If, on the other hand, the arc current is smalL-i't'will not be dissipated throughout a relatively'"'large arc chamber, but, on the other hand, will be confined in the relatively small compartment between partition 60 and end cap 46, to thereby utilize all of this pressure for movingcontact rod 54 away from renewable contact, 52. Similarly, on arcs of intermediate current value, the pressure developed by these arcs is conserved by the successive relatively small sub-chambers formed within arc chamber 42, so

that the full effect of these pressures is effectively utilized for contact separation.

The'upper part of arc chamber 42 is adapted to house a means for biasing contact rod 54 into engagement with renewable contact 52, and to this end a supporting collar'66 is secured to the contact rod 54 as by (a pin 68, and a coil tension spring 64 is secured to supporting collar Be at one end thereof, and the other end thereof is secured to a floating collar 'Hl freely slidably mounted both with respect to contact rod 54 and insulating tube 44, Spring 64- is preferably se- J cured to supporting collars '56 and ill by having the end coils thereof seated in peripheral grooves on reduced extensions of the collars. A coil comasszsao reservoir of arc extinguishing fluid and maintain the pressure required to produce a. flow-of the fluid through the arc chamber for flushing purposes.

Contact rod 54 is connected at the upper end thereof with mechanism designed to move the tacts, with further separation of the contacts being accomplished by the pressures developed in pression spring i2 is provided intermediate spring ti and the inner wall of insulating tube t t, and is seated at one end on floating collar it and at the other end bears againstupper end cap fit.

} It will be apparent that when contact rod 55% is moved upwardly, it will carry the upper end of tension spring as therewith to'stress this spring and exert a force on fioatingsprlng support it to compress spring it, so thatas soon as the force tending to move contact rod Elli away from renewable contact 52 is removed, the springs til and "i2 will operate to reclose the contacts. By the use of the particular spring arrangement illustrated, it is possible to locate a biasing means capable of exerting a relatively large force for biasing the contacts closed, within a relatively small space, so that the contact closing springs may readily be incorporated as part of the arc chamber a The interrupter chamber 62 is provided with outlet apertures ill in top cap it, which are controlled by a pressure and movement responsive valve it. The valve plate it is slidably mounted on contact rod b t, and is provided with a cavity for receiving packing material it? for frictionally associating the valve plate with contact rod 5 3. The lower end of the interrupter unit is provided with inlet apertures 82 controlled by check.

. of used oil and gases provided b the'arc folloW-- ing a circuit interrupting operation and supplying the unitwith fresh oil from casing 2. In other words,- when contact rod 54 is moved away from contact 52 to strike an arc, inlet check valves Bil are chamber 42 as explained above. For this purpose, the upper end of contact rod 56 is pivotally connected as at 85 with one end of a toggle pivotally connected as by a pin 8'17 with one end of a second toggle lever 85, and the other end of toggle lever 86 is pivotallyconnected as by a pin 38 to a piston rod 9t. A piston head 92 is provided at the upper end of piston rod all and is adapted to work in a dashpot cylinder at integral with top cap casting 2b. The upper end of dashpot cylinder 94 is adapted tb be closed ofiby a cover Qt for the top cap casting 23, with the cover being secured to the casting, for example, by'screws 98. The casting 28 preferably supports dashpot cylinder lid by a plurality of radially extending arms Hill to position the cylinder substantially centrally of casting 28, and one of these supporting arms tilt is provided with aipassage compression spring tub, with an adjusting screw ltd for adjusting the stress exerted by spring i 36. Dashpot M is for the purposeof delaying closing action of the circuit breakercontacts, and it will be observed that when the contacts open and piston rod Elli is moved upwardly to move piston head @2 into dashpot cylinder t6, there will be relatively little resistance to this movement because check valve (I lit will be unseated against the pressure exerted by'spring tilt to permit the escape of fluid from cylinder dd. However, when springs (54 and it become operative to reclose the circuit breaker contacts, the check valve tilt will are forced to seat to close inlet passages 82, and

outlet valve plate 16 is carried by contact rod 54" and by the pressure developed within arc cham- I ber 42 into engagement with end cap 40 to close oiT outlet passages 14 and thereby seal the arc chamber so that pressures developed thereon will act solely to move contact rod 54 outwardly. However,'as soon as the circuit is lnterruptedand contact rod 54 starts its downward movement, it

will carry Valve'plate 16 down with it and open outlet passages 14, whereupon, the pressure due to the difference in head of oil between thetop of interrupter chamber 42 and .the bottom of' the chamber will Zcause inlet'check valves to open and permit fiow of oil into the arc chamber at a seat on the outer end of passage W2 and prevent the entrance of fluid tov the upper end of cylinder 94 sothat, in order to move contact rod be downwardly, it is necessary that fluid be forced past piston head 92, which has a relatively close fit in cylinder 94 to, therefore, effectively slow down closing movement of thexbreaker contacts.

. extended to one.side of the toggle levers into a trackway H0 for guiding the knee of the toggle in a predetermined path. As shown in Figs; 1 to 4 inthe normal closed circuit position of the breaker, the toggle is adapted to be positioned substantially at its dead-center position, and is biased by a compression spring 2 to break the toggle vto the right, as viewed in Figs. 1' and 3. Compression spring -I I2 engages between a supporting strip ll4 on piston rod and toggle lever 85, at a point adjacent the knee of the toggle.

-In the normal closed circuit position of the breaker, the toggle is maintained at its deadcenter position by a latch lever H6 engaging a roller 89 on toggle pivot pin ill, and thelatch is maintained in engagement with the pin by a coil compression spring I22 engaging between the latch and upper end cap 40 of the arc chamber. Latch H6 is preferably pivotally mounted on an upwardly extending supporting member I20 integral with top'cap 40 of the interrupter chamber, for example, as by a pivot pin I I8. noted that the trackway groove IIO for pivot pin 8'! at the knee of the toggle is provided with a substantially straight vertically arranged portion I 26, and a curved side track portion I24 communicating with straight portion I26 intermediate the ends of portion I26 and at the lower end thereof. The communication between the lower end of straight portion I26 of groove IIO and curved portion I24 is unrestricted, whereas the communication of the upper portion of side track I24 with straight portion I26 is controlled by a switch lever I28 pivotally mounted, for example, as at I30 on supporting column 38, and resiliently maintained in a position in which it closes oif entrance to side track portion I24, for example, as by a coil tension spring I32 connected between switch lever I28 and a lug on supporting column 38.

In operation, it will be observed that springs 64 and 12 in arc chamber 42 will normally maintain contacts 52 and 54 in engagement; however, when latch lever H6 is depressed to release pivot pin 8I of the toggle. it will be obvious that spring I I2 will be operative to cause collapse of the toggle and movement of toggle pivot pin 81 into the curved portion of track IIO. Inasmuch as piston rod 90 is prevented from moving downwardl by integral inwardly projecting flange I 80 on dashpot cylinder 94. it is obvious that collapse of the toggle and movement of pivot pin 81 into the curved portion I24 of groove I I will cause some movement of contact rod 54 upwardly out of engagement with respect to renewable contact 52. This will establish an arc between the contacts, and the pressure developed by this arc will causefurther upward movement of contact rod 54,, and inasmuch as the knee of the toggle is constrained to follow the path of curved portion I24 of groove H0, it will be caused to move through this curved portion and into the upper end of straight portion I26 of the groove while displacing switch lever I28, and thereby cause movement of dashpot piston 92 to the top of cylinder 04 substantially to the position shown in Fig. of the drawings. As soon as the arc is extin uished within arc chamber 42, springs 64 and 12 will be free to move contact rod 54 towards contact 52 to reclose the same, and the toggle pivot pin 8'! in its downward movement as restrained by dashpot 94 will be caused to move rectilinearly along the straight portion I26 of slot III), because switch lever I28 will prevent movement of pin 81 into the curved portion of groove I I0, and pivot pin 81 will bereengaged by latch lever H6.

The mechanism for causing release of latch lever H6 to .initiate a circuit interrupting oper-- ation is supported from supporting column 38.

As shown, for example, in Figs. 2 and 4, the

It Will be I34 thereof is provided with an angu-- release. levers are maintained in spaced relation by spacing collars I46 also mounted on pivot pin I44, and these levers are each provided with a coil compression spring I48 engaging the upper side of each leveradjacent pivot I44, and a ledge I49 on the supporting arm I36, to bias the levers in a counterclockwise direction about their pivot I44. A bimetal strip I50 which is of conventional form, being composed of laminations I52 and I54 of materials having different coefficients of expansion, intimately bonded together with the lamination I52 preferably having the higher coefficient of expansion so that upon heating of the strip, the upper unsupported end thereof will deflect to the left. as viewed in Figs. 1, 3, 5 and 6, is adapted to control latch lever H6. The lower end of the bimetal strip is secured, for example, as by rivets I56 to support I20, and is insulated therefrom, for example, as by providing sheets of insulating material I58 on opposite sides of the bimetal strip. .An angled supporting bracket I60 is secured to the bimetal strip I50 intermediate the ends thereof, for example,

as by rivets I64, and is insulated from the bimetal strip, for example, by the interposed sheets of insulation I62. Bracket I60, as shown in Figs. 1 and 3, normally supports the outer ehds of release levers I38, I40 and I42 against the bias exerted by their respective biasing springs I 48. The upper end of bimetal strip I50 has secured thereto a latch releasing bracket I66, for example, as by rivets I68, and this bracket is also the upperend of contact rod 54.

insulated from the bimetal strip by the interposition" of sheets of insulation material I10. Toggle latch lever II6 has secured to the outer end thereof a latch releasingrod II2 having an upper forked end for rotatably mounting a roller II4 adapted to be positioned beneath latch release levers I38, I40 and I42, so as to be engageable by each of the latches when they are released.

The circuit through the breaker extends from a terminal (not shown) on the top cap assembly 26 by way of conductor I16 to the upperend of bimetal strip I50, from the lower end of the bimetal strip by way of flexible conductor I18 to When the contacts are in engagement, the circuit con tlnues through renewable contact 52, end cap 46. coil compression spring 50 to contact bolt 6 and conductor I4. It will be observed that bimetal strip I50 is connected in series with the circuit breaker contacts so that load current flows therethrough, and so that'currents above a predetermined value Will be operative to heat the bimetal strip and cause deflection thereof in the manner described above.

In the operation of the circuit breaker shown in Figs. 1 to 6 of the drawings, the parts will be disposed in the normally closed circuit position of the breaker, shown in Figs. 1 to 4 of the drawings, with the contacts maintained closed by springs 64 and I2 and with the knee of the toggle comprising levers 84 and 86 latched substantially at dead-center position by latch lever H6, and with latch release levers I38, I40 and 42 all maintained in an inactive position by'bimetal strip I50. Upon the passage of currents through the breaker above a predetermined value, bimetal strip I50 will be heated and caused to deflect to the left, for example, to the position shown in Fig. 5 of the drawings, and at this position latch release lever I38 will be released because it is shorter than levers I40 and I42. Upon release of latch release lever I38, it will be aes'aseo gagement with toggle pivot pin 87. This will permit the toggle to break to the right, as viewed in Figs. 1 and 3 of the drawings, in the manner described heretofore to separate the contacts and cause movement of the toggle and contact rod together with dashpotpiston 92 to the position shown in Fig. of the drawings. It will be noted that in this movement toggle lever 88 is provided with a laterally projecting reset pin I82 which will pick up latch release lever I38 and latch release levers I40 and I42 as well, in the upward movement of the contact, and its asso ciated parts, to raise them to the position shown in Fig. 5 of the drawings wherein levers N8 and E40 may be engaged by latches 884 and I88, re spectively. It *will be noted that the latch release bracket I66 at the upper end of bimetal strip I50 in the normally closed position of the contacts shown in Figs. 1 and 3, maintains latch levers I84 and I-86 in'a position in which they are out of the path of movement of pins I88 and 90 provided adjacent the outer ends of latch release levers I38 and I40, respectively. However, as soon as the bimetal strip B58 deflects sufficiently to initiate a first circuit interrupting operation (to the position shown in Fig. 5), the latch levers I84 and I86 are permitted to move downwardly under the influence of gravity to a position where latch lever I84 is engageable with pin I88 on latch release lever I38, to maintain this release lever in the position shown in Fig. 5 even upon reclosure 1 of the circuit breaker contacts. I

Accordingly, when the arc is extinguished from the first interrupting operation and springs 64 and I2 reclose the breaker contacts, latch release levers I40 and I42 will be moved into engagement with-bracket I60 on the bimetal strip. In the event the overload on the circuit has cleared in 'the interim, bimetal strip I50 will slowly cool down and gradually resume the position shown in Figs. 1 and 3 of the drawings and eventually engage latch lever I84 causing it to release lever I38 so that the parts will eventually attain'their original position shown in Figs. 1 and 3. However, in the event the overload reniains on the circuit when the contacts reclose after a first closure of the breaker contacts, the bimetal it will iurther deflect to the position shown in Fig. 8 oil the drawings and release the last and longest latch release lever M2 to cause movement of latch lit to release toggle pin 8i, whereupon the contacts will be opened as before. However, there is no latch for maintaining latch release lever I42 in an inactive position so that when springs 64 and'l2 attempt to reclose the breaker contacts athird time, latch release lever 2 will drop to its lowermost position defined by an angular extension I94 of a reset lever I92 pivotally mounted onbracket support I36, and in this p0 sition an integral lug I9! on the upper side oi latch release lever :42 will be positioned in the path of a lookout pin l99.integral with piston rod 90 to prevent downward movement or the ple ton thereof and consequently prevent reengagement of the breaker contacts. Lug till extends from the upper sideof lever I42 laterally at an angle into the path oi movement of pin E88 as shown in Fig. 4. Pin A98 has a slabbed ,ofi side to normally provide clearance with lug 287i. Re= setting lever. I92 is provided with an angula-rly extending portion I96 adapted to extend through an aperture in cover casing 28 and outer cover 200 to provide a visible indication of the condition of the circuit breaker. .In order to reset the breaker contacts after they have become automatically locked open in response to three successive circuit interrupting operations, it is merely necessary to.depress the outer end I96 of the lever to cause rotation of the lever in a clockwise direction and raise latch release lever I42 from the position shown in Fig. 6 until lug I91 thereon is moved out of the path of downward movement circuit interrupting operation, the bimetal strip I will be furthe'ndeflected, and-operate to release the next longest latch release lever I40, to cause release of toggle latch H6 and opening of the circuit in the same manner as before.

This time when the contacts open, their latch release levers are moved to the position shown in Fig. 5 by resetting pin I 82, and latch I86 will have attained a position wherein it is operative to engage pin. I90 on latch lever I40 and maintain this latch release lever as well as latch release lever I38 in an inactive position. Assoon as the circuit is interrupted and coil springs 64 and I2 reclose, latch release leverr I42 will reengage bracket( I on the bimetal strip and the circuit preferably so related are free to reclose the breaker contacts.

. will be noted that extension as latch lever I4Z, ,to i

, avoid undue repetition of lockout pin I89, whereupon springs 64 and 12 Uprelease lever will reseat of this lever on bracket I60 of the and, ofcourse, cooling down of the strip will have released latches I84 and I86 to reset latch release levers I38 and I40 so that the parts 'will resume their positions shown in Figs. l to 4 of thedrawings in readiness for the next overload that comes on the circuit. Of course, each reclosure of the circuit breaker contacts is delayed by the-action of dashpot wardmovement of latch the outer end bimetal strip,

94 topermit the fault on the circuit to clear if it is of the self-clearing type, and also allow sufficient time for flushing of-interrupter unit 42 prior to reclosure of the breaker contacts. It 594 of reset lever I92 ers I38 and I40 as well 'sure resetting of all the latch devers when the outer end I96 of the reset lever is depressed;

extends beneath latch -le In Fig.7 of the drawings, there is illustrated a circuit breaker having many parts like those of the breaker shown in Figs. 1 to 6 of the draw-' lugs and, accordingly, like reference numerals will be used to designate like parts in order to v and to clarify the description of the distinctive parts thereof; In the breaker shown in Fig. 7, the arc chamber 42 is B to insulating casing 2 as to substantially fill the casing, with most of the operating, mechanismcontained in a hollow casing cover structure 204, and instead of utilizing a toggle for slightly separating the breaker contacts -in response to predetermined elec trical conditions as in the embodiment of Figs. 1 to 6, lower end cap46' for the arc chamber is provided with a relatively large central aperture, and serves to clamp between the end cap and partition 60, a

bimetallic disk I98 which is cdncavo-convex in form. Bimetal disk I98 may be of any well knowntype having laminations of different coefficients of expansion so that when the disk is heated, stresses will be set up therein tending to reverse the curvature thereof, and this will take place with a snap'action in a manner well known in the art. The central portion of bimetal disk H99 is apertured for receiving the stern of a combined contact and valve member 200 having an outer head 202, provided for limited sliding movement of the stem thereof with respect to bimetal disk use.

The cover construction 1204 includes a cylindrical casing 205 with a bottom plate 203 secured to the lower end thereof and adapted to seat on the upper end of insulating casing 2, and to have top cap 40' of the interrupter chamber secured thereto, for example, as by bolts 209. Cover casing 205 is, like casing 28 in the embodiment of the invention shown in Figs. 1 to 6 of the drawings, provided with a dashpot cylinder 94 for receiving a piston head 92 mounted on a piston rod I95 integral with contact rod 54. The upper end of dashpot cylinder 94 and the upper end of cover casing 205 are closed like cover casing 28 shown in Figs. -1 to to 6, with a cover 96 secured thereto in any desired manner. Cover assembly 204 is preferably provided with a second dashpot cylinder 206 having a closed upper end pivotally mounted as at 208 on a supporting bracket 2-I0 integral with cover casing 205, Dashpot cylinder 206 is preferably provided adjacent th closed end thereof with a check valve 201 permitting flow of fluid outwardly of thecasing but not inwardly, and the side wall of dashpot cylinder 206 adjacent the open end thereof is preferably provided with an open vent 2H for a purpose to be hereinafter described. Dashpot cylinder 206 is preferably 'biased by a coil spring 2I2 disposed about pivot 208, for movement in a generally clockwise direction about its pivot. A piston rod 2I4 having a head 2I6 for reception within dashpot cylinder 206, is preferably biased outwardly with respect to the dashpot cylinder by a coil compression spring 2I3 engaging the piston head 2I6 and the bottom of dashpot cylinder 206. The outer end of piston rod 2I4 is provided with a notch 2I8 adapted to receive the transverse end portion 220 of a cross bar 222 secured to, piston rod I95. A fixed abutment 224 may be formed integral with cylindrical casing 205 of the cover assembly, and this abutment includes a vertically extending upper surface 226 and an ofiset vertically extending lower surface 230, con-' nected by an inclined intermediate surface 228 adapted to form a track for rollers 232 (only one shown) at opposite sides of rod 2 I4, and mounted on a pin 234 provided on piston rod 2I4.

The circuit through the breaker shown in Fig. 7 preferably-extends from a terminal (not shown) on hollow cover assembly 204, through a flexible conductor 233 to piston rod I95,-con'- tact rod 54, contact 200 to the center of b'imetal disk I98, thence to the outer edges of disk I98, lower cap 46, compression spring 50 and contact bolt 6. Therefore, it will be seen that bimetal disk I98 is connected in series through the breaker constituting .this embodiment of the invention, so as to be responsive to the passage of currents through the circuit above a predetermined value to reverse the curvature thereof.

In the operation of the breaker shown in Fig. '7, and assuming the parts to be in the normal closed circuit position shown on the drawings, upon the passage of overload currents therethrough bimetal disk I98 will be heated to reverse the curvature thereof and movecontact 209 out of engagement with the lower end of contact rod 54 and draw an arc therebetween. The pressure developed within arc chamber 42 will cause movement of contact rod 54 away from contact 200 in the same manner as in the embodiment of Figs. 1 to 6. However, this upward movement of contact rod 54 will also cause movement of piston 2I6 into dashpot cylinder 206. As soon as the arc is extinguished, springs 64 and '32 will cause reclosure of the breaker contacts, as explained in connection with the previously described embodiment of the invention, with this-reclosure, of course, being delayed by the action of dashpot cylinder 94. Dashpot spring 2I3 is preferably relatively weak so that it will move its piston 2I6 outwardly of dashpot cylinder 206 a great deal slower than piston 92 is moved outwardly of dashpot cylinder 94. As soon as contact rod 54 moves towards contact 200, cross bar 222 will become disengaged from piston rod 2I4 and thereby permit spring 212 to rotate dashpot cylinder 206 in a clockwise direction about its pivot 208 until rollers 232 on piston rod 2I4 engage the surface 226 of abutment 224. When the breaker contacts are reclosed by downward movement of contact rod 54 and return of bimetal-disk I98 to the position shown in Fig. 7, and assuming that the overload condition on the circuit has been removed, dashpot piston 2I6 will continue to be slowly moved downwardly by spring 2I3 with its roller successively moving along surfaces 226, 228 and 230 of abutment 224. As rollers 232 move alon inclined surface 228 of abutment 224, one of the rollers will engage a lateral flange 240 on the upper end of a lockout lever 236 pivotally mounted on bottomplate 203, to move this lever in a clockwise direction about its pivot until thisroller 232 moves from under the lower end of fiange240, whereupon the lookout lever will be returned to the position shown in Fig. 7 by a coil spring 221 located at its pivot. However, if the overload condition has not been removed from the circuit, then after the contacts have reclosed, bimetal disk I98 will again reverse its curvature to strike an arc and cause a circuit interrupting operation as before. By this time, dashpot piston 2I6 will only be about halfway out of dashpot cylinder 206 and roller 232 will be substantially at the dotted line position shown in Fig. 7. Accordingly, contact rod 54 and piston rod I95 with piston 92 are free to move upwardly and then reclose the circuit after interruption takes place without affecting dashpot cylinder 206 or piston 2I6. If the overload condition has been removed, after the second reclosure, dashpot piston 2I6 will continue to move out of cylinder 206 and rollers 232 will move along the surfaces of abutment 224 as before, to reset notch 2I8 thereof in' engagement with transverse end 220 of cross bar 222, as shown in Fig. 7. cleared upon the second reclosure, operation of the breaker bimetal disk I98 will again cause a circuit interrupting operation, and this will again take place Without affecting dashpot piston 2I6. However, upon attempted reclosure this time, one roller 232 on dashpot piston rod 214 will have engaged flange 240 on lever 236 to move this lever in alclockwise direction about its pivot so that the notch 238 in the upper-end" Howeveiyif'the fault still has not.

ascrgeeo thereof is in the path of downward movement .of transverse end 226 of cross bar 222, to thereby prevent reclosure of the contact;

To reset the breaker to normal operating condition following an automatic lockout operation of the contacts, a link 235 is pivoted to the end of cross bar 222 opposite transverse portion 220,

neath flange 240 on lockout lever 236, so-that the lever may resume its normal position shown in Fig.'7, whereupon by release of lever 23'! the breaker contacts will be closed by springs 64 and i2 as before.

The vent 2 in the side of dashpot cylinder 202 is provided so that after roller 232 passes from beneath flange 240 on the lookout lever 236, movement of dashpot piston M6 and piston rod 2M will take place rapidly until the movement is halted by engagement of notch 2l8 with end portion 220 of cross bar 222. Arc chamber 22 ,in this embodiment of the invention is flushed out after each circuit interrupting operation by providing an outlet passage 24! extending longitudinally of contact rod- 54 and which is opened as soonlas the upper end of -the-passageenters the cover assembly 204 to permit the escape of;

chamber, and gravity flow is obtained into the lower end of the arc chamber'by the check valve action of contact 200. It will be observed that the lookout action in this embodiment of the invention is dependent upon the lapse of a time predetermined by the characteristics of dashpot 206, and is not dependent upon any particular number of successive operations as in the embodiment described in connection with Figs. 1

tot, of the drawings. Also, iri this embodiment of the invention the contacts are first separated to establish an arc to provide for further contact separation by pressures developed by the arc struck by a bimetal disk, rather than by the toggle arrangement shown in Figs. 1 to 6.

In Fig. 8 of the drawings there is shown a slightly modified form of arc chamber and contact construction somewhat .along the lines of the embodiment shown in Fig. 7, but with different contact separating means; In this embodiment of the invention, the insulating casing 2 is provided with a contact bolt 244 through a central aperture in the closed bottom of the casing and secured in position, for example, by

which is slidably mounted therein.

nuts m. Beneath the head or bolt 244 there is provided a leaf'spring 248 for contact with the lower terminal plate of the breaker assembly. The insulating tube 44 for the interrupter.

chamber is provided adjacent the lower end thereof with spaced sleeves 262-for position-- ing a partition disk 250 similar to the disks 56 and 58 of the first described embodiment of the invention, and a contact block 256 of conducting material such, for example, as copper or the like,

is maintained in position at the lower end of tube 44 by a lower terminal cap' 254 threadedly engaging the lower end of tube 44. The con-' 54 so that the rod may engage the top of con-.

tact block 256 and close the top of bore 258. Cap

254 is provided with a central cylindrical bore 262 adapted to receive a piston-like contact-266, he upper portions of the walls of cylindrical bore 262 are preferably provided with peripherallye spaced grooves 26% adapted to be aligned with radial 256 for apurposeto be hereinafter described,

,The lower cap 254 for the arc chamber supports a contact plate 226 by -means insulating spacing and supporting means 265, and plate 268 is adapted to pivotally support an insulating toggle lever, 216 at one end thereof, with 10 the other end of the lever pivotally connected to Tone end of a toggle lever 212, and the other endof this lever being pivotally connected to contact piston 266. Each of the toggle levers is grooves in the lower surface of contact, block provided with an integral lateral extension; with toggle lever 2'56 having the lateral extension 214%,

and toggle lever 212 having a shorter lateral ,extension are with is pivoted catch 21c at the to bias this lever for movement in a counter-V,

25 clockwise direction bout its supporting pivot to break the toggle to he left, as viewed in Fig. 8, from its normal position adjacent dead center.

A bimetal strip 266 is insulatedly supported at its upper end-on end cap 254, andis provided with-a projection 288 at its lower end for engagenient with pivoted catch 2% on toggle lever 212, to restrain the toggle from movement under the influence of biasing spring 264.

A flexible bellows 290 is adapted to be supported on contact plate 266 and is adapted to be filled with a, fluid capable of uniform expansion uponbeing heated within a predetermined range,

such, for example, as chlorinated ,diphenyl, and

- a resistance heating element 292 is positioned 40 Within the bellows for heating the fluid to obtain expansion of the bellows. The upper end of the bellows is provided with an actuating projection 294 having an angular extension 296 positioned to be engaged by the lower end of bimetal strip 286 when in its normal position shownin Fig. 8. The circuit through the interrupter shown in Fig. 8 extends fromficon'ductor 298 which may be connected to a terminal on the top cover assembly for casing 2, througha main circuit when the breaker contacts are closed, by way of iconductor 300 to contact rod 54, conducting block 256, contact piston 266, toggle link 212, flexible ,-conductor 302 to the upper end of bimetal strip 286, through the bimetal strip, conductor 365 to contact plate- 268 which is engaged by leaf spring i 248 and completes the circuit to terminal bolt 244. An auxiliary contact closing circuit extends from conductor 298, through conductor 304 to one terminal of bellows heater292, through the heatet toangular extension 296 on the bellows actuator, to the lower end of bimetal strip 286, and conductor 305 toterminal bolt 244.

In the operation of this embodiment of the in-' vention, it will be observed" that since bimetal strip 286 is in series in the main current path through the interrupter, it will be' deflected to the left uporifheating' of the 'strip by currents aboveapredetermined value to release theouter end of pivoted toggle lever 216 and permit the toggle to be broken toithe left bybiasingspring 264, to thereby draw contact piston 266 downwardly ment of contact piston 266 is limited by engageout of engagement with contact block 256 anddraw an arctherebetween. Downward movement of toggle lever extension2'l4with bellows -54 is moved downwardly into engagement with contact block 256 after the circuit hasbeen interrupted, the circuit through the breaker will not be reclosed until bimetal strip 286 has cooled down sufficiently to deflect back substantially to its original'position shown in Fig. 8 wherein it engages extension 296 of bellows actuator element 294 to complete the circuit through the bellows heating element 292. fiow through this circuit, inasmuch as the main All of the current will then circuit through contact rod 54 and contact piston 266 is still open, and this will cause heating of resistor 292 to heat the fluid within the be]- lows and cause expansion thereof and engagement of actuator 294 withextension 214 of to gle lever 210 to'move the toggle towards its deadcenter position, and relatch pivoted extension 2'18 beneath catch 288 on bimetal strip 286. The extension 218 is pivoted with respect to toggle.

lever 212 in order to permit deflection of the lever to pass catch 288 on the bimetal strip during its resetting movement. .01" course, as soon as the toggle is reset in the position shown in Fig. 8, contact piston 266 will reengage contact block 256 to reestablish the main circuit through these contacts, and since this main circuit contains less resistance than that of ,the shunt circuit through bellows heater 292, the main current path will flow through this main circuit and through bimetal 286 so that the breaker is restored to a condition wherein it is again ready to interrupt tion shown in Figs. 1 to 6 of the drawings.

ence numerals will be used to designate like parts and the description of these parts will not be repeated in detail.

The insulating tube 44 for the arcing chamber is provided with a lower end cap 306, and the end cap is provided with a central aperture for receiving a contactpiston rod 308 pivotally connected at its lower end to an operating lever 3H], for example, as by a pivot pin 3i 2 engaging in a slot M3 in operating lever cm. 0 One end of the operating lever 310 is pivotally mounted as at 3 on an upwardly extending support BIB integral with the lower leg 3|8 of an L-shaped bracket formed on lower end .cap 306, and a coil compression spring 320 is positioned between the other end of the actuating lever and leg 3|8 of the supporting bracket, for' biasing the actuating lever in a counterclockwise direction about its pivot .3l4 to move contact piston rod 308 upwardly into engagement with contact rod 54. A stop lug 322 is provided integral with the L- shaped supporting bracket for limiting upward movement of actuating-lever 3H3. Cap 306 is provided with spaced apertures for inlet check valves 324 similar to those previously described in connection with the embodiment of the invenbellows 326 similar to the bellows 290 previously the circuit in the event of the occurrence of current above a predetermined value.

In this embodiment of the invention, contact separation and final reclosure are both under the control of electroresponsive means, that is, a

bimetal strip and electrically heated bellows respectively, and the time delay for reclosure of e pot 94 as in the previously described embodiments. From the foregoing. it will follow that if the lookout and reclosing spring means shown in Fig. 7 are utilized with the construction shown in Fig. 8 of the drawings, dashpot 94 for delaying closing movement of the contact rod 54 may be entirely eliminated since this function is taken over by bimetal strip 286 as described above. The upper end of the interrupter unit is preferably vented by contact rod passage 24] as in Fig. 7, and fresh oil may flow into the bottom-of the unit through grooves 264 as contact piston 266 is closed. I

In F.g. 9 of the drawings,jthere is illustrated a means for securing initial contact separation somewhat similar to that shown in Fig. 8, and for use with reclosing and lockout means, for example, like that shown in Fig. 7, but in this embodiment of the invention a bellows arrangement is utilized for securing initial separation, and reclosure of the contacts is obtained by a'spring; Inasmuch as many of the parts of this embodiment of the'invention are identical with those of previously described embodiments, like refer described, is provided with a resistor- 328 and this is connected in the circuit through themterrupter by a flexible conductor 330 connected to contact piston 308, and by a'conductor 332 connected to an insulated contact rivet 334 extending through an aperture in leg 3|8 of the supporting bracket, and insulated therefrom by an insulating collar 336, to engage head 338 of terminal bolt 340.

In the operation of this embodiment of the invention, it is obvious that the passage of currents above a predetermined value through the breaker will cause sufiicient heating of bellows resistor 328 as to expand the bellows to cause engagement of the actuating projection 3 42 thereof with an integral lug 344 on actuating lever 310. Continned expansion of the bellows will produce downward movement of actuating lever 310 and withdraw contact piston 308 from engagement with contact rod 54 to establish an arc. This will cause movement of contact rod 54 upwardly to increase the contact separation in the manner previously described, and as soon as the circuit has been interrupted, biasing spring 320 will be effective to move contact piston 308 upwardly to the position shown in Fig. 9 and a biasing means such, for example, as springs 64 and 72 shown in the embodiments of the invention of Figs. 1

.to 7 of the drawings will be free to restore contact rod 54 into engagement therewith. The bellows arrangement for separating the contact shown in Fig. 9 will give a time delay in interrupting a circuit somewhat greater than that of the bimetal strip or disks utilized in the embodiments of the invention previously described.

-The embodiment of the invention shown in' assaeao o for the cover assembly by a conductor 384-secured to the cover, and to dashpo't piston 346.

The lower end of interrupter chamber 42 is providedwith a bottom cap fixture 350 similar to that shown in Fig. 9, in that it is provided with inlet check valves 382 and a central opening for a contact piston 352 adapted to be actuated by an insulating toggle link 354 pivotally connected thereto as at 356,'and a second toggle link 360 pivotally connected to link 354 by pivot pin 358 and, in turn, mounted on one leg 364 of an L-shaped supporting bracket integral with bottomcap356 by a pivot pin 362. A helically wound coiled bimetal element 368 is adapted to be connected between the other leg 36601? the L- shaped supporting bracketgand pivot pin 358 at the knee of the toggle formed by levers 354 and 355, to control movement of the toggle. Bimetal coil 368 issupported on leg 366 of the L-shaped bracket by an insulating supporting bracket 316, and a bimetal strip 312 is also adapted to be supported at one end on insulating bracket 316, and has the other end thereof hook shaped, as-at til, for cooperation with a catch 315 on toggle lever 366.

Normally, the'toggle formed by levers 35d and 366i is maintained by bimetal coil 368 at a posi tion slightly to the left of its dead center position, as viewed in Fig. 10, and against a stop lug Silt integral with leg 36d of the supporting bracket. 7 v

The circuit through the interrupter shown in Fig. 10 extends from the top cover structure through conductor 384, contact rod 56, contact piston 352, flexible conductor 586, bimetal coil flexible conductor 388, bimetal strip 312 to terminal conductor 39!]. The coiled helically wound bimetal 366 is of a' type well-known in the art which, when heated, will act to contract to move the knee pivot 356 of the toggle to the right, as viewed in Fig. 10, and co'nverselywhen cooled down, bimetal coil 363 will act to move the'knee of the toggle in the opposite direction Inasmuch as both bimetal coil 368 and bimetal strip Sli are connected in series in the circuit through the interrupter of Fig. 10, they will both be heated by currents 'passing through the interrupter in excess of a predetermined value. Bimetal strip 3'l2 is of conventional construction comprising laminations of materials having difierent coefilcients ofv expansion with the material of greater coefilcient located at the upper side of the strip so that upon heating,- the outer end of the strip will be deflected downwardly to engage lug 314. Bimetal strip- 312 should be correlated 'with respect to bimetal coil 366 so that repeated heatings of the strip are required to bring the hooked end 31l thereof into thepath of movement of lug 314, whereas a single heating of coil 368 will suflice to move the toggle knee pivot 358 ,to the right an amount sufilcient to withdraw contact piston 352 from contact 54 and establish an arc thereb'etween. Thereupon contact rod 54 will be moved upwardly to interrupt the circuit by the pressure generated in arc chamber 42 by the arc, and when the circuit has been interrupted, springs 64 and 12 will return contact rod 54 delayed by the action of dashpot cylinder 348, substantially in the same manner as in Fig. 10, by bimetal coil sea. The circuit'will Now if the overload condition on the circuit-- has been cleared after this first reclosure of the contacts, the bimetal strip 312 will merely continue to cool down until it resumes its position shown in Fig. 10, and the parts will be ready for the next overload condition which occurs. How-= ever, if the overload remains on the circuitafter' the first reclosing operation, a circuit interrupting operation is again initiated bybimetal coil 366 and carried through, as before, and this time bimetal strip 312 has the outer end thereof, 31L deflected downwardly a greater distance than the first time. The circuit is reclosed after the second successive interrupting operation as before, arid ii the fault has cleared on this reclo= sure, the bimetal strip 312 will eventually resume its original position shown in Fig. 10. If the fault has not cleared on the second reclosure, the circuit is again opened and this time bimetal strip 3?? is heated a further amount sufiicient to bringthe hooked end 316 thereof into the path of movement of lug 314 when moved to the right in the circuit interrupting operation, to thereby become engaged by hook 31! and pre vent movement of toggle knee pivot 358 to the left by bimetal coil 368 when it cools down, thereby locking the breaker contacts in their open circuit posltion. The upper end of lug31fl is inclined with respect to the vertical away from bimetal strip 312, and the hook 31! on the strip is similarly inclined so that cooling'of strip 312 will not exert sufficient force to disengage these parts.

After the breaker contacts have been locked open, they may be reset only by a manual operation, and to this end manually operable reset rod .318 is provided which may extend through the breaker cover assembly, and it has an angularly extending lower end 380 extending into 3 proximity below bimetal strip 312, to exert sufll- In Fig. 11 of the drawings, there is shown modified form of operating mechanism and lockout means for a circuit breaker, and this mechanism has been shown as applied spec cally to .a breaker having an operating rod con truction,

and which may also have an arc chamber constructionlike that illustrated in Figs. 1 to 6 of the drawings. Since many of the parts shown in to 6, and at the upper end of the toggle a pisdescribed in connection with previous embodi-flo ments of the invention. As stated above; bimetal strip 312. will also be heated, but it will not be heated an amount sufllcient to bring the hooked end 31! thereof into the path of movement of lug 314 when it is moved to the right, as viewed 16 ton rod 392 is provided which carries piston head 92, and slidably passes through an apertured lug 394 on supporting column 395 depending fromthe cover structure. to the latch lever H6 in the first described embodiment'of the invention, is pivotally mounted as at 400 on the supporting frame for engaging A latch lever 398 similar I the toggle pivot 81, to normally maintain the toggle adjacent its dead center position. An upwardly projecting support 402 on a flange of supporting column 395 is adapted to pivotally support an actuating cam wheel 404, which is provided with a shaft 406 pivotally mounted on support 402. The wheel 404 is provided with stop projections 408, M and 2 which project from the periphery of the wheel at progressively greater distances from the center of the wheel, respectively. Actuating projections H3, H4 and M! are also provided on the periphery of wheel 404, and these projections preferably are located at the same radii with respect to the center of the wheel and are spaced angularly the same amount as stop projections 400, 410 and M2. A coil tension spring M6 is connected between a" pin Ml on wheel 404 and an integral apertured lug M9 on the supportingbase, to normally bias wheel 404 in a clockwise direction about its pivot axis 406. Movement of the wheel under the influence of spring 4l6 is normally prevented by a bimetal strip 4E8 mounted on an integral projection 420 on the supporting base, and insulated therefrom, for example, as by a strip of insulating material 422. The upper end of bimetal strip4 I0 is provided with an insulating stop projection 424 secured thereto, and adapted to engage stop projections 408, 0 and H2, and in the normal position of the breaker it will be in engagement with stop projection 408, as shown in Fig. 11. Actuating projections M3, M4 and M on wheel 404 are adapted to engage and actuate an actuating rod 420 integral with latch lever 398, and this rod is provided with an integral lug 420 against which one end of a coil compression spring 430 is adapted to seat, with the other end of the spring seated on the supporting flange integral with the supporting col-' umn 395. This spring 430 will obviously bias latch 398 into engagement with toggle pivot pin The circuit through the interrupter shown in Fig. 11 is adapted to extend through a flexible contact rod 54. -This obviously provides bimetal.

strip 42 8 in a series circuit through the interrupter so that the strip will be responsive to currents above a predetermined value to deflect the upperend thereof to the left, as viewed in Fig. 11, and ,release operating wheel 404 for movement under the influence of its biasing spring 4H5.

-When the wvheel 404 is released for movement by deflection of bimetal strip 448, actuating projection 4l5 will move rod 426 downwardly, and thereby release latch 398 from toggle pivot pin 0? and permit the toggle to break to the right and interrupt the circuit in a manner previously described in connection with the embodiment of the invention shown in Figs. 1 to 6 of the 'drawings. When the contact rod 54 moves upwardly in the circuit interrupting operation, piston rod 392 will also be moved upwardly and this will, in turn, cause lug 454 integral therewith to move dashpot piston 446 to the upper limit of its travel.

81. A lateral extension 432 of support 402 is provided for supporting a bracket 434 having spaced apertured flanges for slidably receiving a lockout pin 436,which, in turn, has a flange 440 acted on by compression spring 438, to normally maintain the pin against the surface of a cam 442 fixed on shaft 406, so as to be movable with actuating wheel 404.

It will be noted that there is provided a second dashpot cylinder 444 preferably formed integral with the cylinder 04 for receiving a piston 446 on a piston rod 448 slidably mounted in the aperture of lug 396. A coil compression spring 450 is provided in dashpot cylinder 444 for normally biasing piston 446 outwardly, and a check valve controlled .outlet 445 is provided in the upper end of the cylinder to permit the passage of fluid out of the cylinder, but to close off this passage when fluid attempts to enter. Adjacent the lower end of dashpot cylinder 444 there is provided a further aperture 452 for a purpose to be hereinafter described. The lower end of dashpot piston rod 448 is provided with an integral resetting lug 453 which is adapted under certain conditions to engage a resetting lever 462, pivotally mounted on support extension 432, and havi g the opposite end 484 thereof engageable wit pin 4|! on actuating wheel 404. Piston rod 448 also extends into the path of movement of an integral actuating lug provided on piston rod 392, so that dashpot piston 446 is moved to the top of its stroke every time the contacts are opened. The outerend of actuating lug 454 on piston rod 392, is provided with a. pivoted catch 458 which is norreclosed as in the first described embodiment of the invention with the reclosing action delayed, of course, by dashpot cylinder 04. Dashpot cylinders 94 and 444 have different characteristics, in that the cylinder 444 and its piston will have a considerably longer time delay than that of cylinder 94, so that when the contacts are reclosed after an interrupting operation dashpot piston 446 will have been moved by spring 450 only a'iraction of its travel out of cylinder 444. Actuating wheel 404 after stop lugs 408 has been released by deflection of the bimetal strip, will move only the distance from stop lug 408 to lug 410, and the latter lug will engage projection 424 on the bimetal, because it is a greater distance from the center of the wheel than projection 408.

Now, in the event that the circuit has been cleared after the first reclosing operation, the contacts will remain closed and dashpot piston 446 will slowly move out of cylinder 444 until resetting lug 453 on piston rod 448 engages resetting lever 462 to rotate actuating wheel 404 in a counterclockwise direction and reset projection 408 on the bimetal catch 424. However, in the event the overload has not cleared after the first reclosing operation, the bimetal 4I8 will be deflected further to release projection 4H0 and permit movement of the wheel a distance, corresponding to that between projections M0 and M2, where its movement will again be arrested by catch 424011 the bimetal, and this will cause actuating projection M4 on the wheel to engage rod 426 on latch 398, to release the toggle pivot pin 81 and cause another circuit interrupting operation. This time the circuit will be interrupted as before and reclosed, and at the time aaszeao ing projection 4l3 releases latch 398to cause a third interrupting operation as before, but this time cam 442 which moves with wheel 404v will project lockout pin 436 into the path of movement of the pivoted catch 456 on dashpot piston rod392, so that in any attempted reclosure of the circuit breaker contacts, contact rod 54 will be prevented from moving downwardly to reengage the other breaker contact. I

After the breaker shown in Fig. 11 has been automatically locked in an open circuit position,

as described above, dashpot piston 446 will continue its movement outwardly of cylinder 444 and finally will engage reset lever 462 to reset actuating wheel 404 an amount sufiicient to reset lug M2 in engagement with bimetal stop 424. This will move cam 44? out of engagement with pin 46. However, this will not affect the condition of the circuit breaker, and it will remain locked open until a manually operable actuating lever 414 is raised to lift piston rod 392 by means of a connecting link 4772 connected to a lug 470 integral with the piston rod. This lifting action of the piston rod will remove pivoted catch 456 from lockout pin 4%, and permit the pin to be retracted by spring 438, so that when manual. actuating lever H4 is released, the contacts will be reclosed in the normal manner. If no overload is present on the circuit on this reclosure, piston 446 will descend and reset actuating wheel 404 to the position shown in Fig. 11. It should be noted that the vent 452 in dashpot cylinder 444 permits a rapid final resetting movement of glgghpot piston 452 in resetting actuating wheel a In Fig. 12 of the drawings there is illustrated a circuit breaker very similar to that shown in Fig. 7 of the drawings with the addition to" the structure of Fig. 7, of certain controls to insure positive separation of the breaker contacts on an interrupting operation in response to relatively low overload currents. Inasmuch as most of the parts of-this breaker are identical with that or" the breakenillustrated in Fig. 7, like reference numerals will be used here to designate like parts. As shown in Fig. 12, an actuating rod adapted to be pivotally supported on a bracket 498 insulated from the cover assembly by insulation 500, and the contact lug 494 thereon is adapted to engage a fixed contact 496 also supported on bracket 498 when contact lever 492 is maintained in: the position .shown, by bimetal strip 488.

One terminal of heating element 4830f the bellows is connected to terminal conductor 486 by a conductor 504, and the other terminal of the heating conductor is connected to the fixed contact 496 so that the heating element is in a high resistance shunt circuit with respect to the main current path through the breaker.

Bimetal strip 488 is preferably correlated with respect to bimetal disk I98 so as to deflect together to separate contactZilU from contact rod 54 at the same time bimetal strip 488 releases contact lever 442. Accordingly, assuming that the bimetal strip and disk are deflected by relatively high currents, an arc will be struck between contact rod 54 and contact Zflil which, because of the high current valiie thereof, will immediately generate suflicient pressure to separate the contacts and extinguish the are before heating element 4% of the bellows has had an opportunity to become heated sufficiently to cause expansion of the bellows. However, in the event that the current interrupted is of a relatively low value, so that the are formed between contact rod 54 and contact 2610 is incapable of generating sufiicient pressure in the arc chamber to cause enough separation ofthe contact to extinguish the arc, after the main circuit has been opened by deflection of bimetal strip 488 so that the circuit then passes through the heating element 433 of the bellows, this will gradually heat up and cause expansion of the fluid within the bellows to exert a stress on operating projection 480 which finally will overcome the holding force of detent 484, and raises actuating lever'4'l6 and consequently piston rod I95 and contact rod 54 through lever 231 and connecting link 235, with a quick action because of the forces stored to overcome the action of 'detent 484, and thereby positively separates the breaker contacts to in-' 4'55 is. connected to reset lever 231 by a pin and slot connection 418, and the lower end of this rod is adapted-to be connected to an actuating pin 419 on the actuating projection 48!! ,of a bellows 482. This bellows may be of the same type previously disclosed in connection with Figs.

8 and 9 of the drawings, and includes a resistance heating element. 483. Normally, the actuating projection 480 of the bellows is latched in the position shown in, Fig. 12 by a spring pressed detent 484 engageable in a peripheral groove 485, near the outer end of projection 4B0; Detent 484 is constructed to permit expansion of the bellows upon the exertion of sufiicient force to cam the detent out of groove 485 against the bias of the detent spring.

The bellows 482 is connected in a shunt circuit through the breaker in the following manner. One terminal conductor 486 of the breaker extends through an insulating bushing in the cover assembly,' andthe main circuit through the breaker continues to the lower end of a bimetal strip 468, insulatingly' supported on a bottom plate ,203 of the cover assembly as at 490, through the bimetal strip to a pivoted contact lever 492, contact 496, flexible conductor 502 to dashpot pistonrod I95 and contact rod 54, contact 200, bimetal 19.8, spring 50 to the head 8'of terminal bolt 6. Pivoted contact lever 452 is terrupt the circuit on such low current operation. It will be noted that each time contact rod 54 moves upwardly and carries cross arms 222 therewith, a resetting pin 489 on connecting link .235 will engage contact lever 492 to reset the safne in engagement in the upper end of bimetal 468. Accordingly, in this embodiment of the invention provision is made for positively insuring interruption of the circuit on eitherhigh or low current operation, with the high current-operation being accomplished primarily by fluid pres-' sure generated in the arc chamber by the are itself, and when the current interrupted is so low as to be incapable of generating enough fluid pressure to separate the contacts, separation is positively eifected by bellows 482.

In the foregoing description there has been specifically disclosed novel circuit breaker con structions especially of the self-contained type,

which are adapte'd'to automatically reclose a circult after a circuit interrupting operation thereof, and in the event of a plurality of closely successive interrupting. operations, the breaker is adapted to automatically reclose the vcircuit a predetermined number of times, after which the breaker contacts are automatically locked in an open circuit position, requiring a manual resetting operation to again place the breaker in serv-- ice. More specifically, the various embodiments- Also various lockout schemes have been disclosed which are especially adapted for use with the fluid pressure type of contact separating means, and these include either mechanical counting means, or means for locking the breaker open controlled by a timing means which is set into operation by the first circuit interruption of any. series of successive interrupting operations to lock the contacts open after a predetermined time has elapsed. There has also been disclosed lockout means which is controlled directly b electroresponsive means for initiating contact separation. There has also been herein disclosed a breaker of the type employing pressure separation of the contacts which is especially designed to operate on both high and low currents, and this is accomplished either by special design of the arc chamber, or by an auxiliary electroresponsive means for positively producing contact separation on low current interruptions.

Having described preferred embodiments of the invention in accordance with the patent statutes, it is desired that the invention be not limited to the particular embodiments herein disclosed,. inasmuch as it will be obvious particu- .larly to persons skilled in the art that many changes and modifications, may be made in these particular structures without departing from the broad spirit and scope of this invention. Accordingly, it is desired that the invention be interpreted as broadly as possible, and that it be limited only by what is expressly stated in the following claims and by the prior art.

Iclaim as my invention: I

1. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, means for separating said contacts to establish an arc, at least one of said contacts being capable of movement away from the other of said contacts to further increase separation of said contacts independently of said contact separating means, said one contact slidably mounted in an aperture provided in a wall of said chamber whereby the fluid pressure generated by said are will be efiective to move said one contact outwardly with respect to said chamber and cause said further contact separation, fixed partition means having a single aperture in which said one contact is slidably mounted, said partition means forming in said chamber a sub.- chamber in which the initial separation of said contacts occurs to eifeotively utilize the fluid pressure developed by small current arcs, and said slidable contact also being slidable through said aperture to permit the drawing of large current arcs outside of said sub-chamber.

2. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an fective to move said one contact outwardly with respect to, said chamber and cause said further contact separation, fixed partition means having a single aperture in which said one contact is slidably mounted-said partition means forming in said chamber a small sub-chamber in which the initial separation of said contacts occurs to effectively utilize the fluid pressure developed by small current arcs, said slidable contact also being slidable through said aperture to permit the drawing of large current arcs outside of said subchamber, and means for moving said contacts into engagement in response toxthe extinction of said arc.

3. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, means operable in response to a condition of the circuit for separating said contacts to establish an arc, at least one of said contacts being capable of movement away from the other of said contacts to further increase separation of said contacts independently of said contact separating means, said one contact slidably mounted in an aperture provided in a wall of said chamber whereby the fluid pressure generated by said arc will be eifective to move said one contact outwardly with respect to said chamber and cause said further contact separation, fixed partition means having a single aperture in which said one contact is slidably mounted, said partition means forming in said chamber a small are in said chamber, means for separating said contacts to establish an arc, at least one of said contacts being capable of movement away from the other of said contacts to further increase separation of said contacts independently of said pressure generated by said arc willv be efsub-chamber in which the initial separation of said contacts occurs to effectively utilize the fluid pressure developed by small current arcs, and said slidable contact also being slidable through said partition means to permit the drawing of large current arcs outside of said sub-chamber.

4. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, means for separating said contacts to establish an arc, at least one of said contacts being capable of movement away from the other ofsaid contacts to further increase separation of said contacts independently of said contact separating means, said one contact slidably mounted in an aperture provided in a wall of said chamber whereby the fluid pressure generated by said are will be effective to move said one contact outwardly with respect to said cham-- her and cause said further contact separation, spaced partitions each having a single aperture 'in which said one contact is slidably mounted,

said partitions dividing said chamber into compartments, whereby when said contacts separate th arc is drawn through said compartments successively, s

5. In a circuit interrupter, an arc chamber which. is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, means for separating said contacts to establish an arc, at least one of said contacts being capable of movement away from the other of said contacts to further increase separation of said contacts independently of said contact separating means, said one contact slidably mounted in an aperture provided in a wall of said chamber whereby the fluid pressure generated by said arc will be effective to move said one contact outwardly with respect to said chamber and cause said further contact separation, and resilient means biasing said contacts into engagement and including a plurality of coil springs arranged coaxially with said one c'ontact assaeco' and reacting between said one contact and a relatively fixed abutment,

6. In a circuit interrupter, an arc chamber.

which is closed at least during circuit interrup- ,tion, separable contacts adapted to establish an arc in said chamber, means for separating said contacts to establish an are, at least one 018E161 contacts being capable of movement away from the other of said contacts to further increase A separation of said contacts independently of said contact separating means, said one contact slidably mounted in an aperture provided in a wall of said chamber whereby the fluid pressure generated by said are will be eflective to move said ed to be stressed in tension and compression,

respectively, upon movement of said one contact away from the other of said contacts.

which; is closed at least during circuit interruption, separable contacts adapted to establish an arc in said the other of said contacts to further increase separation of said contacts independently of said contact separating means,l said one contact slidably mounted in an aperture provided in a wall of said chamber whereby the fluid pressure generated by said are will be effective to move said one contact outwardly with respect to said chamber and cause 'said further contact separation, and. resilient means in said chamber for biasing said contacts into engagement, and including coaxially arranged coil springs reacting between said onecontact anda wall of said chamber.

. 8. In a circuit interrupter, an arc chamber which is closed at least during circuitfnterruption, separable contacts in said chamber at least 'one of whichiis slidably mounted in an aperture provided in one wall of said chamber, means biasing said slidable contact into engagement with the other of said contacts, actuating means for moving said slidable contact away from the other of said contacts at least an amount sufflcient to draw an arc, said slidable contact being movable way from said other contact independently of developed by said are in said chamber, control means for controlling said actuating means to .open the circuit and including a plurality of movable, relatively oflset control portions, and electroresponsive means normallly maintaining said control means in an inactive position and operative in response to predetermined circuit condi= tions to move in one direction to successively releas said control portionsand cause successive sponsive to the absence of said predetermined circuit conditlonsifor resetting said control means. 9. In a circuit interrupter, separable contacts, means for interrupting the circuit including a plurality of spaced, relatively oiiset control portions movable to cause separation of said contacts to interrupt the circuit, and electroresponsive means engageable with said portions for normally maintaining said circuit interrupting means in an inactive position and operative in re-- sponse to predetermined circuit conditions to move in the direction said portions are ofiset to '7. In a circuit interrupter, an arc chamber;

chamber, means for separating said contacts to establish an arc, at least one of said contacts being capable of movement away from circuit interrupting operations, and means reare successively release said control portions and cause successive circuit interrupting operations,

means responsive to the absence of said prede termined circuit conditions for resetting said circuit interrupting means, and means responsive to a circuit interrupting operation for reclosing said contacts.

7 10. In a circuit interrupter, separable contacts,

means for interrupting the circuit including 'a pluralityof spaced relatively ofiset control por= tions movable to cause separation of said con tacts .to' interrupt the circuit, electroresponsive means engageable with said portions for normally maintaining said circuit interrupting means in an inactive position and operative in responseto predetermined circuit conditions to move ln the direction in which said portions are offset to successively releas said control portions and cause successive circuit interrupting operations, means responsive to the absence of said predetermined circuit conditions for resetting said circuit in terrupting means, means responsive to a circuit interrupting operation for reclosing said con tacts, and means responsive to a predetermined number of successive interrupting operations to release all of said control portions for preventin reclosure oi said contacts,

iii, In a circuit interrupter, separable contacts, means for interrupting the circuit including a plurality of levers for causing separation of said contacts, said levers having relatively offset latch portions, electroresponsive means normally en,- gaging said latch portions for maintaining said levers in inactive positions and operative in re sponse to predetermined circuit conditions to move-in on direction and successively release said latch portions to thereby cause successive j circuit interrupting operations, and said electro- Bit said actuting moms in response to fluid pressure responslvemeans movable in an opposite direction to normal position in response to the absence of said predetermined circuit conditions to reset said levers in their aforesaid normal position.

12. In a circuit interrupter, separable contacts, means for interrupting the circuit including a plurality of relatively offset control portions movable to cause separation of said contacts to interrupt the circuit, electroresponsive means nor= mally maintaining said circuit interrupting ,means in'an inactive position and operative in response topredetermined circuit conditions to move in one direction to successively release said control portions and cause successive circuit in terrupting operations, means responsive to the absence 0f said predetermined circuit conditions for resetting said circuit interrupting means,

means responsive to a circuit interrupting operationior reclosing. said contacts, means responsive to release of all of said control portions, for pre venting reclosur of said contacts, and said reset ting means including timing means actuated in,

response to a first circuit interrupting operation to reset said circuit interrupting means a prede tel-mined time thereafter,

13. Jim a circuit interrupter, an arc chamber 5 which is closed at least during circuit interrup tion, a contact member in said chamber, a con-= one end to said rod and havin tact rod slidably mounted through a wall of said cber into and out of engagement with said contact member and biased into engagement with said contact member, toggle means connected at v the other and mounted for movement substantially in the direction 01 movement or said rod, means limiting movem nt oi said other end of said toggle toward said contact member so that in the engaged positoggle means is maintained adjacent its dead cen ter position, means biasing said toggle means to break the toggle and move said contact rod away from said contact member, latch means normally restraining said biasing means, and electroresponsive means operative to release said latch means and permit said toggle biasing means to b open the circuit and establish an arc, and said contact member and biased into engagement with said contact member, toggle means connected at one end to said rod and having the other end mounted for movement substantially in the direction of movement of said rod, means limiting movement of said other end of said toggle toward said contact member so that in the engaged position of said contact rod and contact member said toggle means is maintained adjacent its dead center position, means biasing said toggle means I to break the toggle and move said contact rod away from said contact member, latch means normally restraining said biasing means, eiectro-' responsive means operative to release said latch means and permit said toggle biasing means to open th circuitv and establish an arc, said toggle means permitting overtravel of said contact rod in response to pressure developed in said chamher by the arc, and means operative in response to said overtravel for resetting said toggle means rection of movement of said rod, means limiting movement of said other end of said toggle toward said contact member so that in the engaged position of said contact rodand contact member said toggle means is maintained adjacent its dead center position, means biasing said toggle means to break the toggle and move said contact rod away from said contact member, latch means normally restraining said biasing means, control means operative to release said latch means and permit said toggle biasing means to open the circult and establish an arc, said toggle means permitting overtravel of said contact rod in response to pressure developed in said chamber by the arc, means operative in response to said overtravel for resetting said toggle means in a. position to be reengaged by said latch means upon movement of said contact rod into engagement with said contact member, said control means including a plurality'of movable, relatively offset control portions, electroresponsive means normally maintaining said control means in an inactive position and operative in response to predetermined circuit conditions to move in one direction to successively release said control porin a position to be reengaged by said latch means 2,387,820 tion of said contact rod and contact member saidtions and cause successive circuit interrupting operations, and means responsiveto the absence of said predetermined circuit conditions for resetting said control means.

16. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, snap acting electroresponsive means operative in response to predetermined circuit conditions for moving one of said contacts away from the other an amount at least suificient to establish an arc, the other of said.

contacts being movable away from said one contact to further increase separation of said contacts independently of said electroresponsive means, said other contact being slidabl-y mounted in an aperture provided in a wall of said chamber, whereby the fluid pressure generated by said are will be effective to cause said further contact separation.

17. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, electroresponsive means operative in response to predetermined circuit conditions for moving one of said contacts away from the other an amount at least sufficient to establish an arc, the other of said contacts being movable away from said one contact to further increase separation of said ontacts independently of said electroresponsive means, said other c0ntact being slidably mounted in an aperture provided in a wall of said chamber, whereby the fluid pressure generated by said arc will be effective to cause said further contact separation, means for moving said other contact toward said one contact in response to a circuit interrupting operation, and said electroresponsive'means being operativea predetermined time after a circuit interrupting operation to reset said one contact into engagement with said one contact.

18. In a circuit interrupter, separable contacts, electroresponsive means for separating said contacts to interrupt the circuit, means responsive to a circuit interrupting operation for reclosing said contacts, and timing means adapted to be, actuated only by the first interrupting op eration of any series of closely successive interrupting operations for terminating said series of operations a predetermined time after said first operation.

19. In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts adapted to establish an arc in said chamber, electroresponsive means controlling a toggle for moving one of said contacts toward and away from the other of said contacts to close the circuit, and open the same at least an amount sumcient to establish an arc, respectively, and the other of said contacts being movable away from said one contact to further increase separation of said contacts independently of said electroresponsive means, said other contact being slidably mounted in an aperture provided in a wall of said chamber, whereby the fluid pressure generate by said are will be effective to cause said further contact separation.

20; Ina circuit interrupter, a closed arc cham- 'ber, separable contacts adapted to establish an arc in said chamber, electroresponsive means controlling a toggle for moving one of said contacts toward and away from the other of said contacts to close the circuit, and open the same at assaezo movable away from said one contact to further increase separation of said contactsindependently of said electroresponsfve means, said othercontact being slidabl mounted in an operature provided in'a wall of said chamber, whereby the fluid pressure generated by said are will be ef fective to cause said further contact separation, and a second slower acting electroresponsive means for locking said toggle in a position to maintain said contacts out ofen-gagement in response, to a plurality of operations of said first mentioned electroresponsive means.

21 In a circuit interrupter, an arc chamber which is closed at least during circuit interruption, separable contacts in said chamber, electroresponsive means for separating said contacts at least an amount suflicient to establish an arc, at least one of said contacts being slidably mounted through a wall of said chamber and being capable of movement away from the other of said contacts independently of said electroresponsive means to increase the separation of sai contacts by the force exerted by pressure generated by the arc in said chamber on said one contact, and'a time delay electror'esponsive means for separating said contacts an amount further than said first mentioned electroresponsivemeans,

F whereby to insure sufilcient contact separation to extinguish the are formed, irrespective of the current value thereof.

22. In a circuit interrupter, .anarc chamber ed through a wall of said chamber and being capable ofmovement away from the other of said contacts independently of said electroresponsive means to increase the separation of said contactsby the force exerted by pressure gen 'erated by the arc in said chamber on said one contact, a time delay electroresponsive means for separating said contacts an amount further than said first mentioned electroresponsive means, whereby to insure sufiicient contact separation to extinguish the arc formed, irrespective of the A current value thereof, and said time delay electroresponsive means having a lost motion connection with said contacts to permit said further contact separation under the influence of pres sures developed by the are independently of said second electroresporisive means.

23. In a circuit interrupter, an arc chamber whichis closed at least during circuit interrup tion; separable contacts in said chamber, electroresponsive means for separating said contacts at least an amount s'uiilcient to establish'an are,

I atleast one oifsaid contacts being slidably mountcurrent value thereof, said second elctrorespona sive means being normally independent of the circuit through the interrupter, and means responsive to operation of said first electrorespon sive means to separate said contacts, for connecting said second electroresponsive means in the circuit. I 1

' 24. In a circuit interrupter, separable contacts.

5 means for interrupting the circuit including a plurality of spaced relatively-offset control portions movable to cause separation of said contacts to interrupt the circuit, and electrorespon sive means including a bimetal element engage- .able with said portions for normally maintaining said circuit interrupting means in an inactive position and operative in response to predetermined circuit conditions to move in the direction said portions are offset to successively release 25. In a circuit interrupter, a contact member,

a contact rod slidably mounted for movement into and out of engagement with said contact member and biased into engagement with said contact member, toggle means connected at one end to said 'rod and having the other end mounted for movement substantially in the di= rection of movement of said rod, means limiting movement of said other endof said toggle toward said contact member so that in the engaged position of said contact'rod and contact member said toggle means is maintained adjacent its dead center position, means biasing said toggle means to break the toggle and move said contact rod away from said contact member, latch means normally restraining said. biasing means, and

electroresponsivemeans operative to release said 40 latch means and permit said toggle biasing means to open the circuit and establish an arc.

26. In a circuit interrupter, an arc chamber which is closed at least during circuit interrup= tion, separable contacts adapted to establish an are in said chamber, a snap-acting bimetal element for moving one of said contacts away from the other an amount at least sufficient to establish an arc, the other of said contacts beingmov able away from. said one contact to further increase separation of said contacts independently of said bimetal element, said other contact being slidablylmounted inan aperture provided in a wall of said chamber, whereby the fluid pressure generated by said arc will be effectiveto cause said further contact separation. 27; In a circuit interrupter, an arc chamber which is closed at least during circuit inter-pup -tion, separable contacts adapted to establish an arc in said chamber, an opening in said chamber, flexible bimetal element secured'in said open=-' ing, one of said contacts mounted on said ele ment so as to be moved thereby away from the other an amount at least sufiicient to establish an arc, the other of said contacts being movable away from said one contact to further increase separation of saidcontacts independently of said clementj'said other contact being slidably mount ed in an aperture provided in a wall of said chamber, whereby the fluid pressuregenerated by said 7c are will beeffective to cause said further contact separation, I

28. In acircuit interrupter, separable contacts,

. electroresponsive' means for separating said contacts to interrupt the circuit, means responsive to a circuit interrupting operation forreclosing said 

